Antimicrobial personal care compositions are known in the art. Especially useful are antimicrobial cleansing compositions, which typically are used to cleanse the skin and to destroy bacteria, viruses, and other microorganisms present on the skin, especially the hands, arms, and face of the user.
Another class of antimicrobial personal care compositions is the hand sanitizers. This class of compositions is used primarily by medical personnel to disinfect the hands and fingers. A hand sanitizer is applied to, and rubbed into, the hands and fingers, and the composition is allowed to evaporate from the skin. Wiping of the composition from the skin often is not necessary because the high alcohol content of some hand sanitizers leads to a fast and essentially complete evaporation of the composition from the skin.
Antimicrobial compositions are used, for example, in the health care industry, food service industry, meat processing industry, and in the private sector by individual consumers. The widespread use of antimicrobial compositions indicates the importance consumers place on controlling bacteria and other microorganism populations on skin. It is important, however, that antimicrobial compositions provide a substantial and broad spectrum reduction in microorganism populations quickly and without problems associated with toxicity and skin irritation.
Antimicrobial cleansing compositions typically contain an active antimicrobial agent, a surfactant, and various other ingredients, for examples, dyes, fragrances, thickeners, skin conditioners, and the like, in an aqueous carrier. Several different classes of antimicrobial agents have been used in antimicrobial cleansing compositions. Examples of antibacterial agents include a bisguanidine (e.g., chlorhexidine digluconate), diphenyl compounds, benzyl alcohols, trihalocarbanilides, quaternary ammonium compounds, ethoxylated phenols, and phenolic compounds, such as halosubstituted phenolic compounds, like PCMX (i.e., p-chloro-m-xylenol) and triclosan (i.e., 2,4,4′-tri-chloro-2′-hydroxy-diphenyl ether). Present-day antimicrobial compositions based on such antimicrobial agents exhibit a wide range of antimicrobial activity, ranging from low to high, depending on the microorganism to be controlled and the particular antimicrobial composition.
Hand sanitizers contain a high percentage of an alcohol, such as ethanol. When a high percent of alcohol present in a hand sanitizer, the alcohol itself acts as a disinfectant. In addition, the alcohol quickly evaporates to obviate wiping or rinsing skin treated with the hand sanitizer. Hand sanitizers containing a high percentage of an alcohol, i.e., about 40% or greater by weight of the composition, however, have a tendency to dry and irritate the skin.
Commercial antimicrobial compositions generally provide a low to moderate antimicrobial activity. Antimicrobial activity is assessed against a broad spectrum of microorganisms, including viruses and Gram positive and Gram negative bacteria. The log reduction, or alternatively the percent reduction, in bacterial and viral populations provided by the antimicrobial composition correlates to antimicrobial activity. A log reduction of 3-5 is most preferred, a 1-3 reduction is preferred, whereas a log reduction of less than 1 is least preferred, for a particular contact time, generally ranging from 15 seconds to 5 minutes. Thus, a highly preferred antimicrobial composition exhibits a 3-5 log reduction against a broad spectrum of microorganisms in a short contact time. Prior disclosures illustrate attempts to provide such antimicrobial compositions, which, to date, do not provide the rapid, broad range control of microorganisms desired by consumers.
The use of organic carboxylic acids in antimicrobial compositions is known. One often used aromatic carboxylic acid is salicylic acid. Various investigators have reported improvements in antimicrobial compositions, especially in personal care compositions, that incorporate salicylic acid. For example, Deckner et al. U.S. Pat. No. 5,824,666 discloses oil-in-water emulsions containing salicylic acid as an antiacne agent, and a surfactant, for use as leave-on moisturizing products.
Beerse et al. U.S. Pat. No. 5,968,539 discloses a rinse-off antimicrobial agent containing an antimicrobial agent (e.g., triclosan), a proton donating agent (e.g., salicylic acid), and an anionic surfactant. Other patents that disclose the use of salicylic acid in admixture with an antimicrobial agent include Beerse et al. U.S. Pat. Nos. 6,106,851; 6,183,757; 6,190,674; 6,190,675; 6,197,315; 6,214,363; and 6,287,577. Although these patents disclose the use of salicylic acid in antimicrobial compositions, each disclosure relied upon either (1) an antimicrobial active, such as triclosan, in the composition, or (2) a composition pH of 3.5 or less. Each of the above patents also disclose including a surfactant in the composition.
Prior disclosures have not addressed the use of salicylic acid, or other aromatic carboxylic acids, as the primary, or sole, antibacterial agent present in the antimicrobial composition, especially at a pH of about 3.5 or greater, e.g., about 3.5 to about 5. The prior disclosures also did not address the use of an antimicrobial composition containing an aromatic carboxylic acid as the primary, or sole, antimicrobial agent, and that is free, or at least essentially free, of a surfactant.
Accordingly, a need exists for antimicrobial compositions that are highly efficacious against a broad spectrum of Gram positive and Gram negative bacteria, and viruses, in a short time period, and wherein the antimicrobial activity is attributed primarily, or solely, to the presence of an aromatic carboxylic acid and a hydric solvent in the composition. The present invention is directed to such antimicrobial compositions.